1. Field of Invention
This invention relates generally to pressure-sensitive sealing tapes, and more particularly to a paper-plastic film laminate tape of exceptional strength and sufficient body to enable the tape to be dispensed in a conventional tape dispenser machine.
2. Status of Prior Art
The patent to Williams U.S. Pat. No. 4,351,877 discloses a sealing tape for cartons, formed of a high-strength face ply of synthetic plastic film material, laminated to a base ply of paper whose outer surface is coated with a remoistenable adhesive. This tape is wound into a roll and is dispensed from a standard Kraft paper tape-dispensing machine which includes a water reservoir to moisten the adhesive coating as the tape is advanced out of the dispenser.
As pointed out in the Williams patent, though a sealing tape formed from a thin film of synthetic plastic material is much stronger than a Kraft paper tape, particularly if the film tape is stretch-oriented, a roll of such film tape cannot be dispensed in a Kraft paper tape-dispensing machine.
The reason for this is that the machine relies on the longitudinal stiffness of the paper tape to unwind it from the roll and force it through the outlet of the dispenser where the tape is cut to a desired length. A thin plastic film is unable to be dispensed lengthwise from a Kraft paper or a similar dispenser machine because the flexible plastic film tape is inherently flabby and lacks sufficient rigidity or stiffness for this purpose.
In order, therefore, to add sufficient rigidity to the tape so that it can be properly dispensed, Williams laminates a paper ply to the plastic film ply. To effect lamination of the paper ply to the plastic ply, Williams uses a conventional glue for this purpose. Should this glue be a hot melt adhesive of the type ordinarily used to laminate paper to film, the resultant heat would impair the orientation and strength of the film.
Our above-identified co-pending application Ser. No. 07/975,080 discloses a paper-film laminate sealing tape having a base ply of oriented film, cold-laminated by a water-based adhesive to a paper face ply so that its orientation is maintained, the exposed surface of the film base ply being coated with a remoistenable adhesive. The present invention resides in a pressure-sensitive paper-plastic film laminate tape which is applied to a surface to be sealed by pressure as distinguished from a tape, as in Williams, and in our copending application in which the adhesive layer is remoistenable.